This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Polycystic ovary syndrome (PCOS) is a common disorder of women marked by hyperandrogenemia and ovulatory dysfunction. Additionally, PCOS is associated with obesity and a number of metabolic abnormalities including insulin resistance, glucose intolerance, dyslipidemia, and hypertension. A number of pathophysiological mechanisms underlie PCOS. Neuroendocrine abnormalities play a significant role in most women with PCOS, and PCOS is associated with relative resistance of the gonadotropin releasing hormone (GnRH) pulse generator to negative feedback by progesterone and estradiol. This hypothalamic resistance to negative feedback appears to be a result of hyperandrogenemia (HA), and can also occur in adolescents with HA. We have hypothesized that peripubertal HA-which can represent a forerunner of adult PCOS-can promote the development of PCOS in part via induction of hypothalamic resistance to negative feedback. However, the cause of peripubertal HA remains largely unknown. Obesity is a well-recognized pathophysiological factor in the HA of adult PCOS;and recent data demonstrate that peripubertal obesity is associated with HA. However, the mechanisms underlying the relationship between peripubertal obesity and HA-and the marked variability of androgen levels observed among obese girls-are unknown. We have gathered preliminary data that suggests that obese pre- and early pubertal girls with high androgen levels also exhibit greater degrees of insulin resistance compared to obese girls with lower androgens. The primary goal of this pilot project is to begin to establish the relationship between insulin resistance-as determined by insulin clamp studies-in causing HA in obese peripubertal girls. Secondarily, the investigators aim to assess the contributions of elevated luteinizing hormone-determined by frequent blood sampling for LH-in obesity-associated HA across puberty. Characterization of the factors underlying peripubertal HA may permit prediction of which pre- and early pubertal girls will subsequently go on to develop symptoms of PCOS. Data generated by this project will prompt novel future studies to investigate the complex interactions among metabolic and classical endocrine pathways that lead to PCOS.